Dial type of impulse sender



Feb. 19, 1957 J. E. BOSH DIAL TYPE OF IMPULSE SENDER Filed Dec 26 1951FIG. 6

INVENTOR- JAMES E. BOSH BY WM W ATTORNEY United States. Patent DIAL TYPEor IMPULSE SENDER Application December 26, 1951, Serial No. 263,399

2 Claims. (Cl. 74-152) This invention relates to a dial type of impulsesender, or calling device, such as is commonly employed in automatictelephone systems. The main object of the invention is to provide asimple and reliable sender, or calling device, of this type whichproduces a minimum of noise in operation.

The invention is disclosed as applied to a calling device generallyaccording to the Obergfell Patent No. 1,642,822, issued September 20,1927. Such a calling device has a tenhole finger wheel for rotating amain shaft to carry a pawl over a desired number of teeth of a ratchetwheel according to the number of pulses to be sent, When the fingerwheel is released, a spring wound by the rotation drives the fingerwheel back to normal position. When the return movement begins, the pawlengages the last tooth passed over, to clutch the sending mechanism withthe finger wheel, thereby driving the sending mechanism.

A more specific object of the invention is to provide an improved pawlmechanism which avoids the noise and wear incident to the pawl passingover the teeth of the ratchet wheel during the windup movement. Thisobject is attained in the disclosed mechanism by employing adouble-armed pawl having the two arms so coacting with the ratchet wheelthat the desired pawl engagement is secured by a camming action, ratherthan by the usual spring-bias action which drops the pawl successivelyinto the notches of the wheel with a series of hammer blows, withconsequent objectionable wear and metallic clicks.

A special feature of the invention concerns a travelling stop membermovable radially of the ratchet wheel and cooperating with a slopingfixed stop member to stop the return movement of the mechanismaccurately with a minimum of hammer action and noise.

Other objects and features of the invention will appear as thedescription progresses.

The accompanying drawings, comprising Figs. 1 to 7 show a calling deviceembodying the principles of the invention.

Fig. 1 is a front view of the device with the finger wheel removed,Figs. 2 to 4, are a partial front view, a side view, and a rear view ofpart of the mechanism appearing in Fig. 1, showing the ratchet and pawlto a better advantage.

Figs. 5 to 7 are additional rear views of the ratchet and pawl as thefinger wheel is rotated.

Referring to the drawing, Fig. 1 a front view, shows the calling devicewith the finger wheel removed. The finger wheel (not shown) has acentral raised portion which fits over slightly raised hub 10 on plate12, being held in place by a screw which is threaded into aperture 11 ofhub 10. With the finger wheel installed and rotated forwardly in theusual manner as described in the cited patent, the plate 12 is rotatedin the indicated clockwise direction as seen in Figs. 1 and 2, andcounterclockwise as seen from the rear in Figs. 4 to 6. The ratchetwheel 16 stands still while the plate 12 is rotated forwardly, andconsequently pawl 21, pivotally secured toplate 12 by shoulder rivet 30,passes over the teeth of the ratchet wheel. As viewed in Figs. 2 and 3,travelling stop member 32 and frictional spring 36 also are pivotallysecured to plate 12 by shoulder rivet 30. Stop member 32 is providedwith a cam portion 33, which engages stop arm 28 (at the completion ofthe return movement of the mechanism) to jam an integral brake portion34 into en-' gagement with the sloping back portion of its associatedtooth of ratchet wheel 16, to stop the mechanism in its illustratednormal position. When the finger wheel is rotated forwardly the brakeportion 33 of stop 32, passes over the teeth of the ratchet wheel.Friction spring 36 eliminates any mechanical chattering of pawl 21 toinsure its free movement during the operation of thedevice. Spring 36 ispositioned by having its offset tip portion 37 inserted into an aperture27 provided in pawl 21, as seen best in Fig. 3.

Pawl 21 extends from its fulcrum to partially encircle the ratchet wheel16 with two integral arm portions 22 and 23. The engaging arm 22, ofpawl 21, engages an associated tooth of the ratchet wheel at thebeginning of the return movement of the finger wheel to drive theimpulse-sending mechanism. The guiding arm 23 passing over the teeth ofthe ratchet wheel moves the engaging arm 22 into the associated notchbetween the teeth of wheel 16.

Fig. 4 shows the pawl and ratchet wheel in its normal position, whileFigs. 5 to 7 show the relationship between pawl 21 and ratchet wheel 16as the finger wheel is rotated corresponding to the desired digit. Aspreviously noted, the finger wheel (not shown) is rotated by thesubscriber and secured thereto is plate 12, carrying pawl 21. Fig. 4shows the ratchet and pawl in its normal position, while Fig. 5 showsthe relative position of the pawl with respect to its associated teethof the ratchet wheel as the finger wheel is slightly rotated in acounterclockwise direction, as indicated on the drawing. The forwardangular portion 24 of engaging arm 22 engages the sloping back portionof tooth 17, upon further movement of the finger wheel, portion 24 movesguiding arm 23 into the notch between its associated teeth of wheel 16.As the finger wheel is rotated still further angular portion 26 ofguiding arm 23 engages the sloping back portion of tooth 18 moving theguiding arm 23 outward thereby moving the engaging arm 22 about itsfulcrum into the notch between teeth 17 and 19, as shown in Fig. 6. Asthe finger wheel is further rotated the pawl passes over the teeth ofthe ratchet in the same manner as described, until the finger wheelsrotationable movement is stopped by the engagement of the subscribersfinger with the finger stop 15.

The position of the pawl and ratchet wheel before the finger wheel isreleased is shown in Fig. 7, the guiding arm 23 has engaged the slopingback portion of its associated tooth to move the engaging arm 22 intoengaging position. When the finger wheel is released, the plate 12 andits attached pawl 21 is returned to its normal illustrated position asshown in Fig. 4. Upon its return movement portion 25 of pawl 16 engagesthe front face of its associated tooth of ratchet wheel 16 to drive theimpulse sending mechanism. The engaging face of the teeth, of theratchet wheel, and surface 25 of pawl 21 are of an angular designwhereby the engagement of the two surfaces providing a camming action toforce engaging portion of arm 22 still further into its associatednotch.

As the finger wheel is returned to its normal position, cam portion 33,of stop member 32, engages the angular portion of stop 28, therebymoving its brake portion 34 into engagement with the sloping backportion of the associated tooth of ratchet wheel 16 to stop the movementof the driving mechanism.

The provision of stop member 32 prevents any so-called overtravel, whichcould occur on the completion of the return movement of the fingerwheel, by the ratchet being able to rotate an amount equal to theangular distance between its teeth. This distance being the amount oftravel of the ratchet wheel before portion 24, of pawl 21, engages thesloping back portion of the next associated tooth. Cam portion 33 alsoengages arm 22 of pawl 21, to lock the pawl in engagement relationshipwith the ratchet thereby stopping the finger wheel in its normalposition. The final stop position of the finger wheel is so adjusted (bybending stop member 28 in or out) that the indicia seen in Fig. 1 appearcentrally of me finger holes (not shown).

The device is also provided with a limit stop in that plate 12 has anarm 13 which will engage the side of stop 28 if the latter is set toofar out. If this occurs, the return movement stops with a metallicclick, which can be eliminated by the above noted proper adjustment,which provides a small normal clearance between parts 13 and 28.

I claim:

1. In a calling device including a sending mechanism and a rotatablefinger-Wheel member, means for driving the sending mechanism in onedirection only responsive to back and forth rotation of the finger-wheelmember, said driving means including a ratchet wheel and a pawl, theratchet wheel having teeth inclined to promote clutching engagement bythe ratchet for one direction of rotation of the finger-wheel member andto avoid clutching engagement for the other direction of rotation, thepawl having two oppositely acting arms each ending in two angularlydisposed tooth-contacting faces effective during respective directionsof rotation of the finger-wheel memher, both faces of one arm beingdisposed at a nonclutching angle with respect to said teeth, the twofaces of the other arm being disposed respectively at a clutching and anon-clutching angle with respect to said teeth.

2. In a calling device including a sending mechanism and a finger-wheelmember rotatable forward from a stop position and back to such position,means including a pawl carried with the finger-wheel member and aratchet wheel connected with the sending mechanism for driving thesending mechanism only during the said back rotation, the pawl engaginga tooth of the ratchet wheel to rotate such wheel during the backrotation, a rotatable stop member for use in defining the said stepposition and means fixed with the finger-wheel member for supporting itfor movement radially of the ratchet wheel to permit it to pass over theteeth thereof during the forward rotation, and a fixed stop memberengaged by the rotatable stop member to force the rotatable stop memberagainst a tooth of the ratchet wheel as the finger-wheel member reachesits said stop position, to thereby stop the fingerwheel member in itssaid step position and to lock the ratchet wheel against furtherrotation.

References Cited in the file of this patent UNITED STATES PATENTS353,886 Roe Dec. 7, 1886 389,052 Brown Sept. 4, 1888 817,358 Zwilling eta1 Apr. 10, 1906 1,217,176 Hodge Feb. 27, 1917 2,133,469 Obergfell Oct.18, 1938 2,389,695 Stenhammer Nov. 27, 1945 2,428,569 Hunt et a1 Oct. 7,1947 2,655,052 Montalto Oct. 13, 1953

